Young Sun Mok

Mathematical analysis of positive pulsed corona discharge process employed for removal of nitrogen oxides

A mathematical model was proposed to describe the behavior of the removal of nitrogen oxides (NO ) in a positive pulsed corona discharge reactor. The proposed model takes into account radical production at each pulsing and subsequent radical utilization for NO removal. The production efficiencies of radicals such as O, OH, H, and N were derived by considering direct electron impact on dissociation of gaseous molecules, fol- lowed by excitation transfer reactions of excited oxygen atoms. The production efficiencies of those species were used for the model calculations. The proposed model could adequately predict the experimental data. Of the active species present, the ozone (O ) produced by the reaction of O radical with oxygen was found to play the crucial role in oxidation of NO to NO , both theoretically and experimentally.

Decomposition of Ethylene using a Hybrid Catalyst-packed Bed Plasma Reactor System

A series of experiments using atmospheric-pressure non-thermal plasma coupled with transition metal catalysts were performed to remove ethylene from agricultural storage facilities. The non-thermal plasma was created by dielectric barrier discharge, which was in direct contact with the catalyst pellets. The transition metals such as Ag and V2O5 were supported on γ-Al2O3. The effect of catalyst type, specific input energy (SIE) and oxygen content on the removal of ethylene was examined to understand the behavior of the hybrid plasma-catalytic reactor system. With the other parameters kept constant, the plasma-catalytic activity for the removal of ethylene was in order of V2O5/γ-Al2O3¤Ag/γ-Al2O3¤γ-Al2O3 from high to low. Interestingly, the rate of plasma-catalytic ozone generation was in order of V2O5/γ-Al2O3¤γ-Al2O3¤Ag/γ-Al2O3, implying that the catalyst activation mechanisms by plasma are different for different catalysts. The results obtained by varying the oxygen content indicated that nitrogen-derived reactive species dominated the removal of ethylene under oxygen-lean condition, while ozone and oxygen atoms were mainly involved in the removal under oxygen-rich condition. When the plasma was coupled with V2O5/γ-Al2O3, nearly complete removal of ethylene was achieved at oxygen contents higher than 5% by volume (inlet ethylene: 250 ppm; gas flow rate: 1.0 L min; SIE: ~355 J L).

Demonstration of flue gas cleaning by positive pulsed corona discharge process

Pilot-scale pulsed corona discharge process was applied to the removal of SO/sub 2/ and NO/sub x/ from iron-ore sintering due gas. We made use of a two-stage magnetic pulse compression modulator to produce repetitive high voltage pulses. The dependencies of variables such as channel width, voltage level and dust content on power delivery were examined. In this system, we were able to deliver pulse power with peak voltage of 140 kV and peak current of 3.3 kA to the corona reactor. Under spark-over voltage, the energy delivered per pulse was almost similar regardless of the channel width. The energy conversion efficiency of the magnetic pulse compression modulator was not largely affected by the voltage level and the channel width, and around 65%. The dust content in the flue gas up to 4.6 g/Nm/sup 3/ did not have any influence on the power delivery. The maximum energy intensity that can be obtained was 0.5 J/pulse/m and 0.44 J/pulse/m when the channel width was 300 mm and 200 mm, respectively. More than 90% and 80% of SO/sub 2/ and NO/sub x/ could be removed in the corona reactor in the presence of additives such as ammonia (NH/sub 3/) and propylene (C/sub 3/H/sub 6/).